In article , Brian Watson
writes

As far as I can see, I have just one of the little blighters left from
several clumps of spawn.

I have also gained at least two newts which might, I suppose, contribute to
the tadpole deficiency?

Oh yes, most definitely!!
Our frogspawn was surrounded by a circle of hungry newts right from he
day it first appeared.
Fortunately, with a pond full of weed and 161 frogs, we still have a
good supply of tadpoles.

The water has been gently circulating throughout the incubation and growth
period to clean and oxygenate it naturally.

--
Kay
"Do not insult the crocodile until you have crossed the river"